Depending on the particular crop and soil conditions, various liquid fertilizers are applied directly on the soil. These fertilizers are applied by self-propelled or tractor-pulled spray units in a low-pressure system and would include various types such as nitrogen, phosphate, potash, as well as other types of liquid agricultural fertilizers. The spray units which apply the fertilizer to the soil are supplied by larger truck-mounted nurse tanks which are in turn supplied by larger stationary storage tanks. In both of the latter two tank systems mentioned, the present invention is utilized since quite often the liquid fertilizer may sit in either of these tanks for extended periods of time. The filtering device of the present invention is not attempting to filter out very fine particles but rather only those large particles of rust or sludge which may clog the spray nozzles in the application apparatus. The amounts of filter material quite often become substantial and need to be quickly removed from the system. One of these materials is sludge which forms in the fertilizer itself by a process generally referred to as "salting out".
The prior art filtering devices used in fertilizer systems have never been adequate for a variety of different reasons and usually end up being removed from the system and discarded since they quickly clog-up and have no means of on-system flushing or cleaning. The flushing device of the present invention is an up-flow type filter wherein the heavier particles of rust, scale and sludge settle to the bottom of the filter and can be quickly removed from the system by a dump valve located in the sump of the filter. The filtering element, which is a stainless steel mesh screen, can be quickly removed from inside the filter tank by a quick-release latch mechanism; cleaned and returned to the filter tank in a matter of seconds.
While there are numerous prior art up-flow filters, such as for example U.S. Pat. No. 1,424,197, none of these filtering devices provide a means to rapidly remove, clean and replace the filter screen in a very short period of time. For example, the above mentioned patent requires the removal of the tank top and then the removal of the screen element, both of which require the removal and assembly of numerous bolts holding the screen in place and the top on the filter tank.
In the present invention the filter screen can be quickly removed by merely prying a single latch member over its dead-center position and sliding a single filter screen out of the tank. The filter screen provides its own sealing means for sealing the entry slot in the end wall of the tank in the form of a large o-ring stretched around the edge of the screen member.
Therefore the principal object of the present invention is to provide a fertilizer filter having a single rapid removal filtering element with a maximum area which can be quickly removed from the tank for cleaning.
Another object of the present invention is to provide a liquid fertilizer filter which is self-flushing with or without the removal of the filtering element.
Another object of the present invention is to provide a filter element with an optimum filter area for the size of the filter.
Another object of the present invention is to provide a very simplified cylindrical construction with a single element which is highly efficient in both the flush and the filter cycles.